-$Cambridge: exim/doc/doc-txt/NewStuff,v 1.123 2006/11/14 16:40:36 ph10 Exp $
+$Cambridge: exim/doc/doc-txt/NewStuff,v 1.130 2007/01/23 14:34:02 ph10 Exp $
New Features in Exim
--------------------
test from the snapshots or the CVS before the documentation is updated. Once
the documentation is updated, this file is reduced to a short list.
+Version 4.67
+------------
+
+ 1. There is a new log selector called smtp_no_mail, which is not included in
+ the default setting. When it is set, a line is written to the main log
+ whenever an accepted SMTP connection terminates without having issued a
+ MAIL command. This includes both the case when the connection is dropped,
+ and the case when QUIT is used. Note that it does not include cases where
+ the connection is rejected right at the start (by an ACL, or because there
+ are too many connections, or whatever). These cases already have their own
+ log lines.
+
+ The log line that is written contains the identity of the client in the
+ usual way, followed by D= and a time, which records the duration of the
+ connection. If the connection was authenticated, this fact is logged
+ exactly as it is for an incoming message, with an A= item. If the
+ connection was encrypted, CV=, DN=, and X= items may appear as they do for
+ an incoming message, controlled by the same logging options.
+
+ Finally, if any SMTP commands were issued during the connection, a C= item
+ is added to the line, listing the commands that were used. For example,
+
+ C=EHLO,QUIT
+
+ shows that the client issued QUIT straight after EHLO. If there were fewer
+ than 20 commands, they are all listed. If there were more than 20 commands,
+ the last 20 are listed, preceded by "...". However, with the default
+ setting of 10 for smtp_accep_max_nonmail, the connection will in any case
+ be aborted before 20 non-mail commands are processed.
+
+ 2. When an item in a dnslists list is followed by = and & and a list of IP
+ addresses, in order to restrict the match to specific results from the DNS
+ lookup, the behaviour was not clear when the lookup returned more than one
+ IP address. For example, consider the condition
+
+ dnslists = a.b.c=127.0.0.1
+
+ What happens if the DNS lookup for the incoming IP address yields both
+ 127.0.0.1 and 127.0.0.2 by means of two separate DNS records? Is the
+ condition true because at least one given value was found, or is it false
+ because at least one of the found values was not listed? And how does this
+ affect negated conditions?
+
+ The behaviour of = and & has not been changed; however, the text below
+ documents it more clearly. In addition, two new additional conditions (==
+ and =&) have been added, to permit the "other" behaviour to be configured.
+
+ A DNS lookup may yield more than one record. Thus, the result of the lookup
+ for a dnslists check may yield more than one IP address. The question then
+ arises as to whether all the looked up addresses must be listed, or whether
+ just one is good enough. Both possibilities are provided for:
+
+ . If = or & is used, the condition is true if any one of the looked up
+ IP addresses matches one of the listed addresses. Consider:
+
+ dnslists = a.b.c=127.0.0.1
+
+ If the DNS lookup yields both 127.0.0.1 and 127.0.0.2, the condition is
+ true because 127.0.0.1 matches.
+
+ . If == or =& is used, the condition is true only if every one of the
+ looked up IP addresses matches one of the listed addresses. Consider:
+
+ dnslists = a.b.c==127.0.0.1
+
+ If the DNS lookup yields both 127.0.0.1 and 127.0.0.2, the condition is
+ false because 127.0.0.2 is not listed. You would need to have
+
+ dnslists = a.b.c==127.0.0.1,127.0.0.2
+
+ for the condition to be true.
+
+ When ! is used to negate IP address matching, it inverts the result, giving
+ the precise opposite of the behaviour above. Thus:
+
+ . If != or !& is used, the condition is true if none of the looked up IP
+ addresses matches one of the listed addresses. Consider:
+
+ dnslists = a.b.c!&0.0.0.1
+
+ If the DNS lookup yields both 127.0.0.1 and 127.0.0.2, the condition is
+ false because 127.0.0.1 matches.
+
+ . If !== or !=& is used, the condition is true there is at least one looked
+ up IP address that does not match. Consider:
+
+ dnslists = a.b.c!=&0.0.0.1
+
+ If the DNS lookup yields both 127.0.0.1 and 127.0.0.2, the condition is
+ true, because 127.0.0.2 does not match. You would need to have
+
+ dnslists = a.b.c!=&0.0.0.1,0.0.0.2
+
+ for the condition to be false.
+
+ When the DNS lookup yields only a single IP address, there is no difference
+ between = and == and between & and =&.
+
+ 3. Up till now, the only control over which cipher suites GnuTLS uses has been
+ for the cipher algorithms. New options have been added to allow some of the
+ other parameters to be varied. Here is complete documentation for the
+ available features:
+
+ GnuTLS allows the caller to specify separate lists of permitted key
+ exchange methods, main cipher algorithms, and MAC algorithms. These may be
+ used in any combination to form a specific cipher suite. This is unlike
+ OpenSSL, where complete cipher names can be passed to its control function.
+ GnuTLS also allows a list of acceptable protocols to be supplied.
+
+ For compatibility with OpenSSL, the tls_require_ciphers option can be set
+ to complete cipher suite names such as RSA_ARCFOUR_SHA, but for GnuTLS this
+ option controls only the cipher algorithms. Exim searches each item in the
+ list for the name of an available algorithm. For example, if the list
+ contains RSA_AES_SHA, then AES is recognized, and the behaviour is exactly
+ the same as if just AES were given.
+
+ There are additional options called gnutls_require_kx, gnutls_require_mac,
+ and gnutls_require_protocols that can be used to restrict the key exchange
+ methods, MAC algorithms, and protocols, respectively. These options are
+ ignored if OpenSSL is in use.
+
+ All four options are available as global options, controlling how Exim
+ behaves as a server, and also as options of the smtp transport, controlling
+ how Exim behaves as a client. All the values are string expanded. After
+ expansion, the values must be colon-separated lists, though the separator
+ can be changed in the usual way.
+
+ Each of the four lists starts out with a default set of algorithms. If the
+ first item in one of the "require" options does _not_ start with an
+ exclamation mark, all the default items are deleted. In this case, only
+ those that are explicitly specified can be used. If the first item in one
+ of the "require" items _does_ start with an exclamation mark, the defaults
+ are left on the list.
+
+ Then, any item that starts with an exclamation mark causes the relevant
+ entry to be removed from the list, and any item that does not start with an
+ exclamation mark causes a new entry to be added to the list. Unrecognized
+ items in the list are ignored. Thus:
+
+ tls_require_ciphers = !ARCFOUR
+
+ allows all the defaults except ARCFOUR, whereas
+
+ tls_require_ciphers = AES : 3DES
+
+ allows only cipher suites that use AES or 3DES. For tls_require_ciphers
+ the recognized names are AES_256, AES_128, AES (both of the preceding),
+ 3DES, ARCFOUR_128, ARCFOUR_40, and ARCFOUR (both of the preceding). The
+ default list does not contain all of these; it just has AES_256, AES_128,
+ 3DES, and ARCFOUR_128.
+
+ For gnutls_require_kx, the recognized names are DHE_RSA, RSA (which
+ includes DHE_RSA), DHE_DSS, and DHE (which includes both DHE_RSA and
+ DHE_DSS). The default list contains RSA, DHE_DSS, DHE_RSA.
+
+ For gnutls_require_mac, the recognized names are SHA (synonym SHA1), and
+ MD5. The default list contains SHA, MD5.
+
+ For gnutls_require_protocols, the recognized names are TLS1 and SSL3.
+ The default list contains TLS1, SSL3.
+
+ In a server, the order of items in these lists is unimportant. The server
+ will advertise the availability of all the relevant cipher suites. However,
+ in a client, the order in the tls_require_ciphers list specifies a
+ preference order for the cipher algorithms. The first one in the client's
+ list that is also advertised by the server is tried first.
+
+ 4. There is a new compile-time option called ENABLE_DISABLE_FSYNC. You must
+ not set this option unless you really, really, really understand what you
+ are doing. No pre-compiled distributions of Exim should ever set this
+ option. When it is set, Exim compiles a runtime option called
+ disable_fsync. If this is set true, Exim no longer calls fsync() to force
+ updated files' data to be written to disc. Unexpected events such as
+ crashes and power outages may cause data to be lost or scrambled. Beware.
+
+ When ENABLE_DISABLE_FSYNC is not set, a reference to disable_fsync in a
+ runtime configuration generates an "unknown option" error.
+
+ 5. There is a new variable called $smtp_count_at_connection_start. The name
+ is deliberately long, in order to emphasize what the contents are. This
+ variable is set greater than zero only in processes spawned by the Exim
+ daemon for handling incoming SMTP connections. When the daemon accepts a
+ new connection, it increments this variable. A copy of the variable is
+ passed to the child process that handles the connection, but its value is
+ fixed, and never changes. It is only an approximation of how many incoming
+ connections there actually are, because many other connections may come and
+ go while a single connection is being processed. When a child process
+ terminates, the daemon decrements the variable.
+
+
+Version 4.66
+------------
+
+No new features were added to 4.66.
+
+
+Version 4.65
+------------
+
+No new features were added to 4.65.
+
Version 4.64
------------
1. ACL variables can now be given arbitrary names, as long as they start with
"acl_c" or "acl_m" (for connection variables and message variables), are at
least six characters long, with the sixth character being either a digit or
- an underscore. The rest of the name can contain alphanumeric characters and
- underscores. This is a compatible change because the old set of variables
- such as acl_m12 are a subset of the allowed names. There may now be any
- number of ACL variables. For example:
-
- set acl_c13 = value for original ACL variable
- set acl_c13b = whatever
- set acl_m_foo = something
-
- What happens if a syntactically valid but undefined ACL variable is
- referenced depends on the setting of the strict_acl_vars option. If it is
- false (the default), an empty string is substituted; if it is true, an
- error is generated. This affects all ACL variables, including the "old"
- ones such as acl_c4. (Previously there wasn't the concept of an undefined
- ACL variable.)
-
- The implementation has been done in such a way that spool files containing
- ACL variable settings written by previous releases of Exim are compatible
- and can be read by the new release. If only the original numeric names are
- used, spool files written by the new release can be read by earlier
- releases.
+ an underscore.
2. There is a new ACL modifier called log_reject_target. It makes it possible
- to specify which logs are used for messages about ACL rejections. Its
- argument is a list of words which can be "main", "reject", or "panic". The
- default is "main:reject". The list may be empty, in which case a rejection
- is not logged at all. For example, this ACL fragment writes no logging
- information when access is denied:
-
- deny <some conditions>
- log_reject_target =
-
- The modifier can be used in SMTP and non-SMTP ACLs. It applies to both
- permanent and temporary rejections.
+ to specify which logs are used for messages about ACL rejections.
3. There is a new authenticator called "dovecot". This is an interface to the
authentication facility of the Dovecot POP/IMAP server, which can support a
- number of authentication methods. If you are using Dovecot to authenticate
- POP/IMAP clients, it might be helpful to use the same mechanisms for SMTP
- authentication. This is a server authenticator only. The only option is
- server_socket, which must specify the socket which is the interface to
- Dovecot authentication. The public_name option must specify an
- authentication mechanism that Dovecot is configured to support. You can
- have several authenticators for different mechanisms. For example:
-
- dovecot_plain:
- driver = dovecot
- public_name = PLAIN
- server_name = /var/run/dovecot/auth-client
- server_setid = $auth1
-
- dovecot_ntlm:
- driver = dovecot
- public_name = NTLM
- server_name = /var/run/dovecot/auth-client
- server_setid = $auth1
-
- If the SMTP connection is encrypted, or if $sender_host_address is equal to
- $interface_address (that is, the connection is local), the "secured" option
- is passed in the Dovecot authentication command. If, for a TLS connection,
- a client certificate has been verified, the "valid-client-cert" option is
- passed.
+ number of authentication methods.
4. The variable $message_headers_raw provides a concatenation of all the
messages's headers without any decoding. This is in contrast to
$message_headers, which does RFC2047 decoding on the header contents.
- 5. In a DNS black list, when the facility for restricting the matching IP
- values is used, the text from the TXT record that is set in $dnslist_text
- may not reflect the true reason for rejection. This happens when lists are
- merged and the IP address in the A record is used to distinguish them;
- unfortunately there is only one TXT record. One way round this is not to
- use merged lists, but that can be inefficient because it requires multiple
- DNS lookups where one would do in the vast majority of cases when the host
- of interest is not on any of the lists.
-
- A less inefficient way of solving this problem has now been implemented. If
- two domain names, comma-separated, are given, the second is used first to
- do an initial check, making use of any IP value restrictions that are set.
- If there is a match, the first domain is used, without any IP value
- restrictions, to get the TXT record. As a byproduct of this, there is also
- a check that the IP being tested is indeed on the first list. The first
- domain is the one that is put in $dnslist_domain. For example:
-
- reject message = rejected because $sender_ip_address is blacklisted \
- at $dnslist_domain\n$dnslist_text
- dnslists = sbl.spamhaus.org,sbl-xbl.spamhaus.org=127.0.0.2 : \
- dul.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.10
-
- For the first blacklist item, this starts by doing a lookup in
- sbl-xbl.spamhaus.org and testing for a 127.0.0.2 return. If there is a
- match, it then looks in sbl.spamhaus.org, without checking the return
- value, and as long as something is found, it looks for the corresponding
- TXT record. If there is no match in sbl-xbl.spamhaus.org, nothing more is
- done. The second blacklist item is processed similarly.
-
- If you are interested in more than one merged list, the same list must be
- given several times, but because the results of the DNS lookups are cached,
- the DNS calls themselves are not repeated. For example:
-
- reject dnslists = http.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.2 : \
- socks.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.3 : \
- misc.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.4 : \
- dul.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.10
-
- In this case there is a lookup in dnsbl.sorbs.net, and if none of the IP
- values matches (or if no record is found), this is the only lookup that is
- done. Only if there is a match is one of the more specific lists consulted.
-
- 6. All authenticators now have a server_condition option. Previously, only
- plaintext had this, and this has not changed: it must be set to the
- authenticator as a server. For the others, if server_condition is set, it
- is expanded if authentication is successful, and treated exactly as it is
- in plaintext. This can serve as a means of adding authorization to an
- authenticator.
+ 5. In a DNS black list, if two domain names, comma-separated, are given, the
+ second is used first to do an initial check, making use of any IP value
+ restrictions that are set. If there is a match, the first domain is used,
+ without any IP value restrictions, to get the TXT record.
+
+ 6. All authenticators now have a server_condition option.
7. There is a new command-line option called -Mset. It is useful only in
conjunction with -be (that is, when testing string expansions). It must be
followed by a message id; Exim loads the given message from its spool
- before doing the expansions, thus setting message-specific variables such
- as $message_size and the header variables. The $recipients variable is
- available. This feature is provided to make it easier to test expansions
- that make use of these variables. However, Exim must be called by an admin
- user when -Mset is used.
+ before doing the expansions.
8. Another similar new command-line option is called -bem. It operates like
- -be except that it must be followed by the name of a file. For example:
-
- exim -bem /tmp/testmessage
-
- The file is read as a message (as if receiving a locally-submitted non-SMTP
- message) before any of the test expansions are done. Thus, message-specific
- variables such as $message_size and $h_from: are available. However, no
- Received: header is added to the message. If the -t option is set,
- recipients are read from the headers in the normal way, and are shown in
- the $recipients variable. Note that recipients cannot be given on the
- command line, because further arguments are taken as strings to expand
- (just like -be).
+ -be except that it must be followed by the name of a file that contains a
+ message.
9. When an address is delayed because of a 4xx response to a RCPT command, it
is now the combination of sender and recipient that is delayed in
- subsequent queue runs until its retry time is reached. You can revert to
- the previous behavious, that is, delay the recipient independent of the
- sender, by setting address_retry_include_sender=false in the smtp
- transport. However, this can lead to problems with servers that regularly
- issue 4xx responses to RCPT commands.
+ subsequent queue runs until its retry time is reached.
10. Unary negation and the bitwise logical operators and, or, xor, not, and
- shift, have been added to the eval: and eval10: expansion items. These
- items may now contain arithmetic operators (plus, minus, times, divide,
- remainder, negate), bitwise operators (and, or, xor, not, shift), and
- parentheses. All operations are carried out using signed integer
- arithmetic. Operator priorities are as in C, namely:
-
- (highest) not, negate
- times, divide, remainder
- plus, minus
- shift-left, shift-right
- and
- xor
- (lowest) or
-
- Binary operators with the same priority are evaluated from left to right.
- For example:
-
- ${eval:1+1} yields 2
- ${eval:1+2*3} yields 7
- ${eval:(1+2)*3} yields 9
- ${eval:2+42%5} yields 4
- ${eval:0xc&5} yields 4
- ${eval:0xc|5} yields 13
- ${eval:0xc^5} yields 9
- ${eval:0xc>>1} yields 6
- ${eval:0xc<<1} yields 24
- ${eval:~255&0x1234} yields 4608
- ${eval:-(~255&0x1234)} yields -4608
+ shift, have been added to the eval: and eval10: expansion items.
11. The variables $interface_address and $interface_port have been renamed
as $received_ip_address and $received_port, to make it clear that they
relate to message reception rather than delivery. (The old names remain
available for compatibility.)
-12. The "message" modifier can now be used on acl verbs to vary the message
- that is sent when an SMTP command. For example, in a RCPT ACL you could
- have:
-
- accept <some conditions>
- message = OK, I'll allow you through today
-
- Previously, this message modifier would have had no effect whatsoever.
-
- IMPORTANT: The new behaviour applies to "accept" (and "discard") only if
- there is no occurrence of "endpass" in the statement. If "endpass" is
- present, the behaviour reverts to the old case, where "message" applies to
- rejection. This is for backwards compatibility.
-
- It is always possible to rewrite ACL statements so that "endpass" is not
- needed (and indeed it is no longer used in the default configuration, and
- is somewhat not recommended nowadays because it causes confusion.)
-
- It is now generally true that the "message" modifier sets up a text string
- that is expanded and used as a response message if the current statement
- terminates the ACL. The expansion happens at the time Exim decides that the
- ACL is to end, not at the time it processes "message". If the expansion
- fails, or generates an empty string, the modifier is ignored.
-
- For ACLs that are triggered by SMTP commands, the message is returned as
- part of the SMTP response. In this situation, the message may begin with an
- overriding SMTP response code, optionally followed by an "extended response
- code". However, the first digit of the supplied response code must be the
- same as would be sent by default. A panic occurs if it is not. For the
- predata ACL, note that the default success code is 354, not 2xx.
-
- However, notwithstanding the previous paragraph, for the QUIT ACL, unlike
- the others, the message modifier cannot override the 221 response code.
-
- In the case of the "connect" ACL, accepting with a message modifier
- overrides the value of smtp_banner.
-
- The ACL test specified by acl_smtp_helo happens when the client issues the
- HELO or EHLO commands, after the tests specified by helo_accept_junk_hosts,
- helo_allow_chars and helo(_try)_verify_hosts. An acceptance message
- modifier for EHLO/HELO may not contain more than one line (it will be
- truncated at the first newline and a panic logged), and it cannot affect
- the EHLO options.
-
+12. The "message" modifier can now be used on "accept" and "discard" acl verbs
+ to vary the message that is sent when an SMTP command is accepted.
Version 4.63
git://git.exim.org / exim.git / blobdiff